An organic light emitting diode display is a self-emission display device which has an organic light emitting diode which emits light to display an image. Unlike a liquid crystal display, since the organic light emitting diode display does not require a separate light source, it is possible to relatively reduce a thickness and a weight thereof. Further, since the organic light emitting diode display has high-grade characteristics such as low power consumption, high luminance, and a high response speed, the organic light emitting diode display has received attention as the next-generation display device for portable electronic apparatuses.
An organic light emitting diode is an element using light generated when an electron and a hole are coupled with each other to emit light and to dissipate the emitted light. Generally, the organic light emitting diode basically includes an electrode for injecting a hole, an electrode for injecting an electron, and an emission layer, and has a structure in which the emission layer is laminated between a positive electrode which is the electrode for injecting a hole and a negative electrode which is the electrode for injecting an electron. In more detail, when the electron is injected to the negative electrode of the organic light emitting diode and the hole is injected to the positive electrode, charges thereof move in opposite directions to each other by an external electric field and then are coupled with each other in the emission layer to emit light so that the light can be emitted and the emitted light may be dissipated. In the organic light emitting diode, the emission layer is made of a single molecular organic material or a polymer.
Also, the organic light emitting diode display has a multilayer laminated structure, and the light generated from the emission layer is transmitted into the one or more layers of the organic light emitting diode display and thus a ratio of light which is not discharged outside is considerably high. The phenomenon may be caused by a waveguide phenomenon due to total reflection, and it is known that light extraction efficiency in the organic light emitting diode display is considerably low at about 20%. Accordingly, in the organic light emitting diode display, it is very important to increase the light extraction efficiency.